A 12-year-old Palestinian boy has been killed in a third successive day of Israeli strikes on Gaza, according to local medical sources.

Another person was injured. It brings to 17 the number of dead in the Israeli bombardment since Friday.

The death of a Palestinian militant whose car was targeted by Israeli forces in Gaza City has sparked the worst violence the area has seen for almost a year, with Israel on the receiving end of sustained rocket attacks.

The Israeli army confirmed strikes have been carried out and said it was checking reports that a boy had died.

He's said to have been killed in northern Gaza. A Palestinian militant reportedly died in a separate attack.

The escalating violence has brought calls for a ceasefire from the UN, the EU, the Palestinian Authority and Egypt.

Militant groups in Gaza, vowing revenge for the Israeli strikes, have fired more than 100 rockets into southern Israel since Friday.

Six people have been injured, one seriously. The police say several more projectiles have been fired into Israeli territory on Sunday.

Some 25 were intercepted on Saturday before they landed in Israel, according to the military.

The country's defence minister Ehud Barak said its defence system had proved its effectiveness, adding that Israel would strike all those who target Israeli civilians.